Have you ever volunteered for a social good organization and been horrified by the way you were treated? (x-post r/socialcitizens)

I've heard several horror stories from people about how they were completely taken for granted, worked to the bone, and deceived by organizations who claimed to be working to make the world a better place. These people often don't make their comments publicly though; because they are trying to get a job in that industry, and fear that they will be viewed as malcontents. Has anyone else experienced this, or heard of anything like this happening?